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YepAPI
StepFunText Generation/v1/ai/chat

Step 3.5 Flash

Access Step 3.5 Flash through one API key. StepFun's fast model.

StepFun's fast inference model. Budget-friendly Chinese provider with 262K context window.

No credit card required. Takes 30 seconds.

2,400+

Developers

1.2M+

API calls served

100+

Endpoints

$0.01

Per call

Yep, that's it.

Try it live

Send a message and see Step 3.5 Flash respond in real time.

POST/v1/ai/chat

Maximum tokens in the response.

Real-time tokens

Hit "Send Request" to see the response

Context Window

262K tokens

Max Output

66K tokens

Input Price

$0.10 / 1M tokens

Output Price

$0.30 / 1M tokens

Strengths

Speed
Cost-effective
Multilingual
Chinese

Quick start

Copy this snippet and start making calls with Step 3.5 Flash.

const res = await fetch('https://api.yepapi.com/v1/ai/chat', {
  method: 'POST',
  headers: {
    'x-api-key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "model": "stepfun/step-3.5-flash",
    "messages": [
      {
        "role": "user",
        "content": "Explain API gateways in 2 sentences."
      }
    ],
    "maxTokens": 256
  }),
});
const { data } = await res.json();
console.log(data.message.content);

Why use Step 3.5 Flash through YepAPI?

One API key for all models — no separate accounts
OpenAI SDK compatible — just change the base URL
No monthly minimums — pay per token
Switch models with one line of code
Full provider passthrough — citations, search results, and all extras included
Streaming and non-streaming support on every model
Works with Cursor, Claude, LangChain, and any LLM tool
Unified billing across all providers

What developers say

Switched from SerpAPI and cut our SERP costs by 80%. Same data quality, way simpler billing.

Marcus T.

SEO Platform Founder

One API key for AI models, SERP data, and web scraping. Saved us from managing 4 separate providers.

Priya S.

Full-Stack Developer

The $5 free credit let us prototype our entire rank tracking feature before committing. No other API does that.

Jake R.

Indie Hacker

Frequently asked questions

StepFun's fast inference model. Budget-friendly Chinese provider with 262K context window.

Input tokens cost $0.10 per 1M tokens and output tokens cost $0.30 per 1M tokens through YepAPI. No monthly minimums — you only pay for what you use.

Sign up for a free API key, then send requests to the /v1/ai/chat endpoint.

Step 3.5 Flash supports a 262K token context window with up to 66K output tokens per request.

Ready to use Step 3.5 Flash?

$5 free credit on signup. No credit card required. Pay per call.

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